As the demand for diesel boiling range fuel increases worldwide there is increasing interest in sources other than petroleum crude oil for producing diesel fuel. One such source is what has been termed renewable sources. Crude tall oil is one example of a renewable source. Crude tall oil is a side produce of the pulp and paper industry and represents a renewable feedstock that does not compete as a food source. The major components in crude tall oil are free fatty acids, rosin acids, and unsaponifiable hydrocarbons.
The Crude tall oil maybe used as the sole feedstock, or may be used in combination with one or more other renewable sources include, but are not limited to, plant oils such as corn, rapeseed, Camelina, Jatropha, canola, soybean and algal oils, animal fats such as tallow, fish oils and various waste streams such as yellow and brown greases and sewage sludge. The common feature of these additional renewable feedstock sources is that they are composed of glycerides and Free Fatty Acids (FFA). Both of these classes of compounds contain aliphatic carbon chains having from about 8 to about 24 carbon atoms. The aliphatic carbon chains in the glycerides or FFAs can be fully saturated or mono-, di-, or poly-unsaturated.
There are reports in the art disclosing the production of hydrocarbons from oils. For example, U.S. Pat. No. 4,300,009 discloses the use of crystalline aluminosilicate zeolites to convert plant oils such as corn oil to hydrocarbons such as gasoline and chemicals such as para-xylene. U.S. Pat. No. 4,992,605 discloses the production of hydrocarbon products in the diesel boiling range by hydroprocessing vegetable oils such as canola or sunflower oil. Finally, US 2004/0230085 A1 discloses a process for treating a hydrocarbon component of biological origin by hydrodeoxygenation followed by isomerization.
Applicants have developed a process which comprises two or more steps to hydrogenate, decarboxylate, decarbonylate, and/or hydrodeoxygenate and then hydroisomerize the crude tall oil feedstock. Although difficult to see or recognize, and unlike other renewable feedstocks, at room temperature, crude tall oil is a multi-phasic material. So applicants process provides a solution to bring the crude tall oil feedstock into a single phase and maintain the single phase in the process.